Cardiotomy and Venous Blood Reservoir and Method

ABSTRACT

A cardiotomy and venous blood reservoir, including a housing assembly, a venous inlet port, a venous sub-assembly, a cardiotomy inlet port, and a cardiotomy sub-assembly. The housing forms a chamber. The venous sub-assembly includes a downtube and a bowl. A diameter of the downtube lumen increases to a downstream end. The bowl forms a floor surface for receiving flow from the lumen. The cardiotomy sub-assembly includes a dish and an inner post. The dish defines an aperture. The inner post extends from the dish and forms a guide surface received within the central aperture and forming an undulating curvature increasing to a diameter greater than the diameter of the central aperture. Cardiotomy liquid drops from the dish fall on to the undulating, closely positioned guide surface with minimal splashing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/372,362, filed Feb. 17, 2009, entitled “Cardiotomy andVenous Blood Reservoir and Method”, and bearing Attorney Docket No.P0030637.00; and the entire teachings of which are incorporated hereinby reference.

BACKGROUND

The present disclosure relates to combined cardiotomy and venous returnreservoirs. More particularly, it relates to cardiotomy and venous bloodreservoirs with improved air handling and useful with various perfusionsystems, for example in connection with patients requiring lower flowcapacities.

In many surgical procedures, the functions of the heart and lungs areperformed outside of the body by specialized devices such as membraneoxygenators, cardiac assist pumps, and heat exchangers. This array ofequipment is operated by a perfusionist who supervises the removal andreturn of the patient's blood during the surgical procedure. Thepatient's blood is stored in a venous reservoir interposed between thevena cava tap and the pump of the heart-lung machine, which pumps theblood through the oxygenator and back into the patient's aorta. Thevenous reservoir also serves as a fluid butler in the externalcirculation system to smooth out variations between the blood flowavailable from the vena cava and the demands of the heart-lung machinepump. Because a substantial amount of blood escapes into the patient'schest cavity during the surgery, it is necessary to recover thiscardiotomy blood from the operative field (e.g., cardiotomy suction).Once treated (e.g., filtered), the cardiotomy blood can also be returnedto the patient. While the venous blood and the cardiotomy blood can beseparately maintained, it has become conventional in recent years tocombine the cardiotomy and venous blood into a single, hard shellcardiotomy and venous reservoir.

A conventional, combined cardiotomy and venous blood reservoir has twodistinct fluid paths leading to a main chamber: a venous blood path anda cardiotomy blood path. The venous blood path enters the reservoirthrough a centrally located venous intake, and is conveyed into adefoaming chamber in which any air bubbles present in the venous bloodare removed before the venous blood is discharged into the main chamberof the reservoir. The cardiotomy blood enters the reservoir through oneor more cardiotomy inlets, and is conveyed through variousfiltering/defoaming regions where cellular and surgical debris and largeamounts of air are removed from the cardiotomy blood.

While available filters and defoamers employed with cardiotomy andvenous blood reservoirs are highly viable for performing necessary airbubble and particulate removal, in some instances concerns remain. Withpediatric applications (and in particular neonates and infants), theblood volume and maximum flow rates through the surgical perfusioncircuit are reduced (as compared to adult patients). Conventional(adult) cardiotomy and venous reservoirs may be less than optimal underthese circumstances. For example, the reservoir blood flow path(s),while effectuating uniform flow at higher flow rates associated withadults, may introduce discontinuities at the lower flow rates ofpediatric procedures, in turn causing undesirable formation of foam. Inaddition, the relatively small volume of blood within the reservoir (andelevated perfusion circuit cycle rate) increases the opportunities forturbulence and therefore trauma. More particularly, when the volume ofblood is low in the reservoir chamber, a conventional cardiotomy andvenous return reservoir will oftentimes subject the incoming blood flowto a splashing-type flow pattern, undesirably introducing trauma intothe blood. Finally, while the use of defoamers to eliminate foam in thecardiotomy and venous blood within the reservoir is well-accepted, onlyfoamed portions of the blood flow need to contact the defoamer.Conventional practice, however, entails blood flow continuously passingover/through the defoamer(s) and may lead to complications.

In light of the above, any improvements to combined cardiotomy andvenous blood reservoirs will be well-received, especially those thataddress the concerns associated with the low volume and/or low flowrates associated with pediatric applications.

SUMMARY

Some aspects in accordance with principles of the present disclosurerelate to a cardiotomy and venous blood reservoir, including a housingassembly, a venous inlet port, a venous sub-assembly, a cardiotomy inletport, and a cardiotomy sub-assembly. The housing forms a main chamber.The venous sub-assembly forms a venous chamber fluidly between thevenous inlet port and the main chamber. The venous sub-assembly includesa downtube and a bowl. The downtube defines an upstream region, adownstream region, and a lumen extending therethrough. The upstreamregion extends from the venous inlet port, whereas the downstream regionextends from the upstream region and terminates at a downstream endlocated within the venous chamber. In this regard, a diameter of thelumen increases along at least the downstream region to the downstreamend. The bowl is disposed within the venous chamber and forms a floorsurface facing the downstream end for receiving venous blood flow fromthe lumen. The cardiotomy sub-assembly forms a cardiotomy chamberfluidly between the cardiotomy inlet port and the main chamber. Thecardiotomy sub-assembly includes a dish and an inner post. The dishdefines a flow surface open to the cardiotomy inlet port and terminatingin a central aperture. The inner post extends downwardly relative to thedish, and is co-axially disposed over the downtube. Further, the innerpost forms a guide surface defined by a leading segment and a trailingsegment for directing cardiotomy liquid flow from the dish aperture tothe cardiotomy chamber. The leading segment is received within thecentral aperture and has a diameter that is less than a diameter of thecentral aperture. The trailing segment extends downwardly from theleading segment and forms an undulating curvature. In particular, theundulating curvature defines a diameter that is greater than thediameter of the central aperture. With this construction, uponoccurrence of dripping-type cardiotomy liquid flow from the dishaperture, the cardiotomy liquid drops fall onto the undulating, largerdiameter portion of the guide surface in a manner minimizing occurrencesof splashing. In some constructions, the dish forms a knife edge thatdirects cardiotomy liquid drops to fall toward the guide surface. Inother embodiments, the downtube forms one or more exterior ribs forengaging a venous defoamer component of the venous sub-assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a cardiotomy and venous reservoir inaccordance with principles of the present disclosure;

FIG. 1B is a longitudinal, cross-sectional view of the reservoir of FIG.1A;

FIG. 2 is a perspective, exploded view of the reservoir of FIG. 1A;

FIG. 3A is a cross-sectional view of a portion of the reservoir of FIG.1A, including a turret;

FIG. 3B is a top view of the reservoir of FIG. 1A;

FIG. 4A is an enlarged, cross-sectional view of a portion of thereservoir of FIG. 1B, taken along the line 4A;

FIG. 4B is an enlarged, cross-sectional view of a bowl portion of thereservoir of FIG. 1A;

FIG. 5 is a CFD analysis relating to venous blood flow through thereservoir of FIG. 1A;

FIG. 6 is a cross-sectional view illustrating partial assembly of thereservoir of FIG. 1A;

FIG. 7 is an enlarged, cross-sectional view of a portion of anothercardiotomy and venous reservoir in accordance with principles of thepresent disclosure;

FIG. 8A is a top, perspective view of a cover assembly useful with thereservoir of FIG. 1A; and

FIG. 8B is a top, perspective view of the cover assembly of FIG. 8A,including various connectors mounted thereto.

DETAILED DESCRIPTION

A cardiotomy and venous reservoir 20 in accordance with principles ofthe present disclosure is shown in FIGS. 1A and 1B. The reservoir 20includes a housing assembly 22, a venous sub-assembly 24 (best shown inFIG. 1B), and a cardiotomy sub-assembly 26 (best shown in FIG. 1B).Details on the various components are provided below. In general terms,however, the housing assembly 22 defines a main chamber 28. The venoussub-assembly 24 is maintained by the housing assembly 22, and forms avenous chamber 30 through which venous blood flow from a venous inletport 32 is directed into the main chamber 28. The cardiotomysub-assembly 26 is also maintained by the housing assembly 22, andestablishes a cardiotomy chamber 34 through which cardiotomy blood flowfrom one or more cardiotomy inlet ports 36 is directed into the mainchamber 28. In this regard, the venous sub-assembly 24 is constructed toestablish substantially laminar flow of the venous blood to the mainchamber 28, and the cardiotomy sub-assembly 26 is constructed tominimize trauma to the cardiotomy blood flow to the main chamber 28. Thereservoir 20 is highly useful as part of a perfusion circuit, withparticular applicability to patients in which relatively low volumes andflow rates are encountered (e.g., pediatric patients including neonates,infants, and children; small adults; etc.).

The housing assembly 22 can assume a variety of forms, and in someembodiments includes a housing 40, a lid 42, and a turret 44. Thecomponents 40-44 combine to define the main chamber 28, with the lid 42and the turret 44 maintaining one or more ports, such as the cardiotomyinlet port(s) 36.

The housing 40 is a generally cylindrical body defining an upper side 50and a lower side 52. The lid 42 is assembled to the upper side 50, withthe lower side 52 optionally having a contoured shape and terminating atan outlet port 54 that is otherwise fluidly connected to the mainchamber 28. In some constructions, and as best shown in FIG. 1A, thehousing 40 forms a handle segment 56 in a region opposite the outletport 54. The handle segment 56 is sized for convenient grasping by acaregiver's hand, and thus facilitates transporting of the reservoir 20.Further, the handle segment 56 is optionally configured to facilitatemounting of the reservoir 20 to a separate support structure (notshown), such as an upright post (e.g., IV stand). For example, alongitudinal passageway 58 is formed through the handle segment 56, withthe handle segment 56 defining or including a shoulder 60 at the lowerside 52. The passageway 58 is sized to slidably receive the post. Theshoulder 60 serves as a support surface for maintaining the reservoir 20relative to a corresponding feature of the separate support structure.Alternatively, the handle segment 56 can assume a variety of otherforms, and in some embodiments is omitted.

With reference to FIG. 2, the lid 42 is mounted to (or alternativelyformed as part of) the housing 40, and maintains or defines one or moreconnectors 70. For example, in some constructions, the lid 42 forms orprovides luer connectors 70 a, 70 b, a ventilation connector 70 c, and apressure relief valve housing connector 70 d. Additional connectors canalso be formed or provided with the lid 42 and/or one or all of theconnectors 70 a-70 d can be omitted. Regardless, the lid 42 forms acentral aperture 72 sized to rotatably receive the turret 44 asdescribed below. In this regard, the central aperture 72 iscircumscribed by a ridge 74 (best shown in FIG. 1B) optionallyconstructed to promote rotatable mounting of the turret 44 relative tothe lid 42.

The turret 44 is shown in greater detail in FIG. 3A. As a point ofreference, the view of FIG. 3A illustrates the turret 44 in isolation,along with a portion of the cardiotomy sub-assembly 26 (referencedgenerally) and a portion of the venous sub-assembly 24 (referencedgenerally). In particular, and as described in greater detail below, thevenous sub-assembly 24 includes a downtube 80 that is otherwiserotatably maintained by the turret 44.

With the above in mind and with reference between FIGS. 2 and 3A, theturret 44 includes, in some embodiments, an inner hub 90, a base plate92, and a plurality of fingers 94. The inner hub 90 forms a bore 96sized to coaxially receive and maintain the downtube 80. The base plate92 extends radially outwardly from the inner hub 90, and forms ormaintains the cardiotomy inlet port(s) 36. In some embodiments, two ormore of the cardiotomy inlet ports 36 are provided, for example, FIG. 3Billustrates the turret 44 as providing four of the cardiotomy inletports 36. Alternatively, any other number, either greater or lesser, isequally acceptable. Additional fluid connectors can further be formed orcarried by the turret 44, such as a prime connector 98, a luerconnector(s) 100, etc.

Returning to FIGS. 2 and 3A, the plurality of fingers 94 projectlongitudinally downwardly from the base plate 92 and arecircumferentially spaced from one another. In some embodiments, acontinuous outer hub 102 is longitudinally disposed between the baseplate 92 and the fingers 94, and serves to facilitate a fluid tightassembly to the lid 42. Regardless, the fingers 94 are constructed toexhibit a radially outward bias in extension from the base plate 92, andforms a ledge 104. Upon assembly of the turret 44 within the centralaperture 72 of the lid 42, each of the ledges 104 are biased intosliding engagement with the ridge 74 as shown in FIG. 1B. With thisconstruction, then, the turret 44 is rotatable relative to the lid 42(and thus the housing 40), with each of the ledges 104 sliding along theridge 74, thereby maintaining the turret 44 relative to the lid 42. Thelid 42 and/or the turret 44 can have constructions differing from thosedescribed above. For example, the rotational features are optional andcan be omitted. In more general terms, the housing assembly 22 serves toestablish the main chamber 28, as well as flow paths or ports for venousand cardiotomy blood to the reservoir 20 and a flow path or port of thetreated blood from the reservoir 20.

Returning to FIG. 1B, the venous sub-assembly 24 includes the downtube80, as well as a bowl 110, a venous filter 112, and a venous defoamer114. The downtube 80 forms a lumen 116 fluidly connected to the venousinlet port 32. The bowl 110 is located to receive liquid (e.g., venousblood) dispensed from the downtube 80, and to direct the liquid towardthe venous filter 112. Finally, the venous defoamer 114 is positioned tointerface with any foam associated with venous blood accumulated withinthe bowl 110. More particularly, the bowl 110 and the venous filter 112combine to define at least a portion of the venous chamber 30, with thevenous defoamer 114 exposed to foam rising within the venous chamber 30.

The downtube 80 can assume a variety of forms, and in some embodimentsis defined by an upstream region 120 and a downstream region 122. Thelumen 116 extends through the regions 120, 122, with the upstream region120 establishing a fluid connection to the venous inlet port 32.Additional ports, such as a venous sampling port 124, a temperaturemonitoring port, etc., can also be formed or provided. Further, theupstream region 120 can form or define one or more bends 126.Regardless, the downstream region 122 extends from the upstream region120 and terminates at a downstream end 128 fluidly opposite the venousinlet port 32.

The downstream region 122 extends into the housing 40, and thus the mainchamber 28. The downtube 80 can optionally form one or more features,such as a flange 130 and grooves 132, to facilitate rotatable mountingof the downtube 80 within the bore 96 of the lid 42. Regardless, uponfinal assembly of the reservoir 20, the downtube 80 defines a chambersegment 134 extending from the turret 44 to the downstream end 128, withthe downtube 80 being entirely linear along the chamber segment 134 insome embodiments. As illustrated, the linear chamber segment 134 canextend through at least a majority of the height or depth of the mainchamber 28.

As best shown in FIG. 4A, the downtube 80 forms the lumen 116 asincreasing in diameter or flaring to the downstream end 128. Forexample, relative to the chamber segment 134, the lumen 116 can bedefined as having a chamber inlet side 140 adjacent the turret 44, withthe chamber inlet side 140 defining a first or inlet diameter D_(I). Thelumen 116 has a second or outlet diameter D_(O) at the downstream end128. With these designations in mind, the inlet diameter D_(I) is lessthan the downstream or outlet diameter D_(O) (e.g., the inlet diameterD_(I) is on the order of 0.635 cm and the outlet diameter D_(O) is onthe order of 0.9525 cm in some embodiments), with the lumen 116exhibiting a uniform increase in diameter from the inlet side 140 to thedownstream end 128. In some embodiments, the lumen 116 uniformlyincreases in diameter along a majority of a length of the downtube 80;in other embodiments, the increase in lumen diameter is defined along anentirety of the downtube 80 length. Regardless, the flared lumendiameter slows the velocity of the venous blood being delivered throughand along the lumen 116. This effect, in turn, reduces the velocity ofbubbles impinging upon the venous filter 112 (as described below), as abuoyancy of the air bubble forces the air bubble to the free surface ofthe venous blood flow. As a result, air is removed from the venous bloodflow more effectively such that the reservoir 20 exhibits improved airhandling capabilities.

The bowl 110 is positioned to receive venous blood flow dispensed fromthe downstream end 128 of the downtube 80, and forms a floor surface150. In some embodiments, the bowl 110 is an integrally formed componentof the housing 40; alternatively, the housing 40 and the bowl 110 can beseparately formed and subsequently assembled. The floor surface 150serves to guide or direct venous blood flow within the venous chamber30, such that the venous chamber 30 can be viewed as having an inlet atthe downstream end 128 of the downtube 80 and an outlet at the venousfilter 112.

A geometry of the floor surface 150 is selected to provide laminar flowtransition from the downtube 80 to the venous filter 112. For example,and with additional reference to FIG. 4B (that otherwise illustrates thebowl 110 in isolation), the floor surface 150 is defined by a rimsegment 152, an annular shoulder segment 154, an intermediate segment156, and a protrusion 158. The rim segment 152 extends radiallyoutwardly and downwardly from the shoulder segment 154, terminating atan outer edge 160. As described below, the outer edge 160 is positionedimmediately adjacent the venous filter 112. The shoulder segment 154defines an uppermost side of the floor surface 150 (upon finalconstruction of the reservoir 20 and relative to the upright orientationof FIG. 4A), and encircles the downstream end 128 of the downtube 80. Inthis regard, a diameter defined by the shoulder segment 154 is greaterthan an outer diameter of the downtube 80 relative to at least thedownstream region 122 thereof. The intermediate segment 156 extendsradially inwardly and downwardly from the shoulder segment 154. In someconstructions, a transition of the floor surface 150 from the shouldersegment 154 to the intermediate segment 156 is a gentle curve. Theintermediate segment 156 forms or defines a bottom face 162 opposite theshoulder 154, with the bottom face 162 effectively defining a lowermostside of the floor surface 150 (relative to the upright orientation ofFIG. 4A).

The protrusion 158 extends radially inwardly and longitudinally upwardfrom the bottom face 162 of the intermediate segment 156, terminating ata center 164. The center 164 is a generally curved surface, and isspatially positioned above the bottom face 162. As described in greaterdetail below, the curved, raised nature of the protrusion 158, and inparticular the center 164, facilitates laminar flow of liquids dispensedonto the center 164 to the intermediate segment 156. In someconstructions, a height of the protrusion 158 (i.e., linear distancebetween the bottom face 162 and the center 164) is in the range of0.065-0.105 inch; alternatively in the range of 0.075-0.095 inch; and inyet other constructions is 0.085 inch. Further, an outer diameter of theprotrusion 158 can be on the order of 0.1-0.3 inch; alternatively 0.2inch. Other dimensions are also acceptable.

In some constructions, the bowl 110 further incorporates features thatfacilitate assembly of the venous filter 112. For example, the bowl 110can form a trough 170 sized to receive and maintain the venous filter112 immediately adjacent the outer edge 160 of the rim 152. In thisregard, the venous filter 112 can assume a form commensurate withformats conventionally employed for venous blood filtering such as ascreen material (e.g., 64 micron screen). With some constructions, thevenous filter 112 is a pleated screen, formed as an annular ring havinga first side 172 and a second side 174. With this but one acceptableconfiguration of the venous filter 112 in mind, the trough 170 isannular, and is defined in part (as best shown in FIG. 4B) by a basewall 176 and an inner wall 178. A width of the base wall 176 iscommensurate with wall a thickness of the pleated venous filter 112. Theinner wall 178 projects radially inwardly and longitudinally upwardlyfrom the base wall 176, and is configured to capture the first side 172in an abutting-type relationship. The second side 174 is maintained by aportion of the cardiotomy sub-assembly 26 as described below.Alternatively, the venous filter 112 can be mounted relative to the bowl110 in other ways and/or with additional components.

For reasons made clear below, the venous filter 112 can have a taperedshape, with the first side 172 defining an inner diameter greater thanan inner diameter of the second side 174. The trough 170 is constructedto accommodate this tapered construction, with the inner wall 178extending in an angular fashion from the base wall 176. For example,relative to the longitudinal cross-sectional view of FIG. 4B, opposingsides of the inner wall 178 define an included angle A in the range of5°-15°, for example 10°, in extension from the base wall 176.Alternatively, the trough 170 can assume a wide variety of other forms,and/or may be formed apart from the bowl 110.

The venous defoamer 114 can be formed of a material conventionallyemployed for venous blood defoaming (e.g., polyurethane foam). In someembodiments, the venous defoamer 114 is sized for assembly about thedowntube 80, and thus can have a generally tubular constructionterminating at a leading end 180 and a trailing end 183.

Upon final construction of the venous sub-assembly 24, the venousdefoamer 114 is secured about the downtube 80 (e.g., via an optionalelastomeric band 182), and the bowl 110 is positioned generally belowthe downstream end 128. Further, the venous filter 112 is secured withinthe trough 170. The bowl 110 is arranged relative to the downtube 80such that the protrusion 158, and in particular the center 164, isaxially aligned with a center axis of the lumen 116. The center 164 isvertically below and spaced from the downstream end 128 (e.g., a spacingon the order of 0.175-0.195 inch, alternatively 0.185 inch). Conversely,the shoulder segment 154 is spaced radially outwardly from the downtube80, with the downstream end 128 being vertically below the shouldersegment 154. Finally, the leading end 180 of the venous defoamer 114 ishorizontally above the shoulder segment 154, as well as the downstreamend 128 (e.g., an offset distance on the order of 0.6 inch between theleading end 180 and the downstream end 128). In other embodimentsdescribed below, the leading end 180 is displaced from the downstreamend 128 by a distance greater than that reflected by FIG. 4A. Thetrailing end 183 abuts a surface of the turret 44, with a smallventilation region 184 being established above the trailing end 183 fordirecting removed gas through a venous gas pathway 186. Ventilation fromthe venous gas pathway 186 is described in greater detail below.

With the above construction, venous blood flow into the downtube 80 isdirected by the lumen 116 to the downstream end 128. As described above,the flared nature of the lumen 116 serves to reduce a flow velocity ofthe venous blood as it flows to the downstream end 128. The venous bloodis then dispensed from the downstream 128 and onto the floor surface 150of the bowl 110. In this regard, the protrusion 158 disperses the venousblood flow radially outwardly from the center 164 and along theintermediate segment 156. Venous blood accumulates within the bowl 110,rising to a level of the shoulder segment 154. Because the downstreamend 128 is “below” the shoulder segment 154, the downstream end 128 willalso be within a volume of the accumulated venous blood so that primewithin the lumen 116 is not lost even if venous blood flow to thedowntube 80 is stopped. Regardless, the floor surface 150 directs thevenous blood flow from the intermediate segment 158 and to the shouldersegment 154, and from the shoulder segment 154 to the rim segment 152.The rim segment 152, in turn, guides the venous blood flow to the venousfilter 112 where appropriate filtration occurs prior to the venous bloodentering the main chamber 28.

It has surprisingly been found that the desired laminar flow can beachieved and maintained by the downtube 80 and bowl 110 constructions ofthe present disclosure at the low flow rates typically encountered withpediatric cardiac surgery perfusion circuits. For example, FIG. 5illustrates a screen shot of a computational fluid dynamic (CFD)analysis of venous blood flow F from a downtube T to a bowl B inaccordance with the present disclosure. As a point of reference, thescreen shot representation of FIG. 5 is rotated 90° to correspond withan upright orientation of a corresponding reservoir; further, onlyone-half of the flow is reflected (it being understood that flow to the“right half” of the flow shown is identical). The downtube T wasconstructed to have a flaring inner diameter lumen, with a downstreamend E located vertically above a protrusion of the bowl B. The bowl B,in turn, incorporated the geometry and surface features described above(e.g., a protrusion height of 0.085 inch and diameter of 0.20 inch, anda spacing between the downstream end and the protrusion center of 0.185inch). At flow rates on the order of 1.8 liters/minute, FIG. 5illustrates that the flow F was smooth along an entirety of the bowl B,leading to the venous filter (identified generally at VF). This smoothflow is characterized as being substantially laminar (i.e., laminar flowor flow having a Reynold's number within 10% of laminar). As a point ofreference, other constructions encompassed by the present disclosureincorporate substantially laminar, maximum flow rate characteristicsthat are greater or lesser than 1.8 liters/minute, as described below.

Returning to FIG. 4A, the leading end 180 of the venous defoamer 114 isoffset from the above-described venous blood flow path such that thevenous blood does not unnecessarily interface with the venous defoamer114. Instead, any foam associated with the venous blood within thevenous chamber 30 will rise upwardly (relative to the orientation ofFIG. 4A) and only then contacts the venous defoamer 114 to effectuatedesired defoaming. The non-foam portion of the venous blood, however,does not necessarily contact the venous defoamer 114. At elevatedvolumes, the venous blood level within the venous chamber 30 may rise tothe venous defoamer 114, such that in some instances, at least some ofthe non-foam portion of the venous blood will contact the venousdefoamer 114, while at least some of the non-foam portion (i.e., “below”the venous defoamer 114) will not.

The cardiotomy sub-assembly 26 is, in some embodiments, constructed in astacked relationship relative to the venous sub-assembly 24. Forexample, in some embodiments, the cardiotomy sub-assembly 26 includesframework 200, a dish 202, a cardiotomy filter 204 (hidden in the viewof FIG. 4A, but referenced generally), and a cardiotomy defoamer 206. Ingeneral terms, the framework 200 maintains the cardiotomy filter 204 andthe cardiotomy defoamer 206. The dish 202 directs cardiotomy liquid flowfrom the cardiotomy inlet port(s) 36 to the framework 200, with theframework 200, in turn, directing the cardiotomy liquid flow to thecardiotomy filter 204 via a guide surface 208. The filtered cardiotomyliquid is subsequently directed to the main chamber 28 as describedbelow. Further, the cardiotomy defoamer 206 is positioned to selectivelyinterface with primarily the foamed portion of the cardiotomy liquiddelivered to, and maintained by, the cardiotomy chamber 34.

The framework 200 can assume a variety of forms, and in some embodimentsincludes an inner post 210, a base 212, and an outer frame 214. Theinner post 210 can be tube-like, sized to coaxially receive thedownstream region 122 of the downtube 80 as well as the venous defoamer114 (with embodiments in which the venous defoamer 114 is assembled overthe downtube 80). Further, the inner post 210 forms a first section 216of the guide surface 208, serving to direct cardiotomy liquid flowreceived from the dish 202.

The base 212 extends radially outwardly and downwardly from the innerpost 210, and defines a second section 218 of the guide surface 208. Insome constructions, the base 212 is adapted to maintain the second side174 of the venous filter 112, and can form a corresponding trough 220.Thus, in some embodiments, the base 212 serves to additionally form aportion of the venous chamber 30, such that the framework 200 can beviewed as being part of the venous sub-assembly 24. Alternatively,however, the framework 200 can be a component entirely discrete from thevenous sub-assembly 24.

The outer frame 214 extends from the base 212 opposite the inner post210, and in some embodiments includes a series of spaced apart struts222. The struts 222 maintain the cardiotomy filter 204 along an outerdiameter collectively defined by the struts 222, and the cardiotomydefoamer 206 along a collectively-defined inner diameter. For example,the struts 222 can form a neck 224 (referenced generally) against whichthe cardiotomy defoamer 206 is received. In addition, the outer frame214 defines an outlet section 226 of the guide surface 208. The outletsection 226 can be viewed as a portion of the cardiotomy filter 204, asa continuation of the base 212, can be a separate rim component, etc.Regardless, the outlet section 226 serves to direct cardiotomy liquidoutwardly from the cardiotomy filter 204.

The cardiotomy filter 204 can be of a type conventionally employed forcardiotomy blood filtration and thus can be a felt material (e.g., 30micron depth or mesh filter). In some constructions, the cardiotomyfilter 204 is a pleated depth or mesh filter, formed as a ring and thuscircumscribing the framework 200. Even further, the framework 200 is anintegral component of the cardiotomy filter 204. Regardless, thecardiotomy filter 204 is positioned immediately adjacent the outletsection 226 of the guide surface 208.

The cardiotomy defoamer 206 is also of a type conventionally employedfor cardiotomy liquid defoaming (e.g., polyurethane foam), and isassembled to the framework 200 so as to be spaced from the guide surface208. For example, relative to the first section 216, the cardiotomydefoamer 206 is spaced radially outwardly from the guide surface 208.Relative to the second section 218 and the outlet section 226, thecardiotomy defoamer 206 is vertically above the guide surface 208. Acircumferential gap 234 is formed between the flow surface 232 and theguide surface 208 at the aperture 230, and is optionally on the order of0.100 inch in some embodiments. With this construction, and as describedin greater detail below, flow of cardiotomy liquid along the guidesurface 208 need not necessarily interface with the cardiotomy defoamer206 and the circumferential gap 234.

The dish 202 can have a funnel-like shape, and forms a central aperture230. As shown in FIG. 4A, the dish 202 is configured for mounting to thehousing assembly 22 (e.g., the turret 44), with a flow surface 232 ofthe dish 202 being fluidly open to the cardiotomy inlet port(s) 36 (bestshown in FIG. 1A). The central aperture 230 is coaxially disposed aboutthe inner post 210, with the flow surface 232 terminating in closeproximity to the first section 216 of the guide surface 208. With thisconstruction, then, the dish 202 directs cardiotomy liquid flow from thecardiotomy inlet port(s) 36 to the guide surface 208 via the flowsurface 232/aperture 230.

In some embodiments, the cardiotomy sub-assembly 26 is mounted to and inconjunction with the venous sub-assembly 24. For example, FIG. 6illustrates partial assembly of the reservoir 20, including the bowl 110formed in or by the housing 40, and the venous filter 112 mounted to thebowl 110. The framework 200 is mounted to the venous filter 110, withthe cardiotomy filter 204 being assembled to, or formed by, theframework 200. More particularly, the base 212 is mounted to the secondside 174 of the venous filter 112. With reference to FIGS. 2 and 4A, thevenous defoamer 114 is sandwiched between the downtube 80 and the innerpost 210. The dish 202 is assembled about the inner post 210, forexample by mounting of the dish 202 to the turret 44, followed byassembly of the turret 44 relative to the housing 40. A cardiotomyventilation gap 236 is defined between the outer frame 214 of theframework 200 and the dish 202. The cardiotomy ventilation gap 236 isfluidly open to the main chamber 28, and facilitates release of gases(e.g., gaseous microemboli) from the cardiotomy chamber 34 and thevenous chamber 32 to the main chamber 28 as described below. Upon finalconstruction, the inner post 210 and the cardiotomy filter 204 combineto at least partially define the cardiotomy chamber 34, with the guidesurface 208 defining a flow path through the cardiotomy chamber 34.

More particularly, and with specific reference to FIG. 4A, cardiotomyliquid entering the reservoir 20 via the cardiotomy inlet port(s) 36 isdirected by the dish 202 (via the flow surface 232) to the inner post210. The cardiotomy liquid transfers from the dish 202 to the firstsection 216 of the guide surface 208 via the central aperture 230. Thecardiotomy liquid flows (via gravity) along the first section 216 of theguide surface 208 to the second section 218, and then to the cardiotomyfilter 204. Any foam associated with the cardiotomy liquid otherwiseaccumulating along the second section 218 “behind” the cardiotomy filter204 rises upwardly and into contact with the cardiotomy defoamer 206.However, non-foamed portions of the cardiotomy liquid do not necessarilyinterface with the cardiotomy defoamer 206. At elevated volumes, a levelof the non-foamed portion of the cardiotomy liquid can rise to thecardiotomy defoamer 206 such that at least some of the non-foamedportion contacts the cardiotomy defoamer 206, while at least some (i.e.,non-foamed portion “below” the cardiotomy defoamer 206) does not.Regardless, the cardiotomy liquid is subsequently filtered by thecardiotomy filter 204.

With the one arrangement of FIG. 4A, following interface with thecardiotomy filter 204, the cardiotomy liquid is directed from the outletportion 226 and onto the venous filter 112. More particularly, thecardiotomy filter 204 is located directly above the venous filter 112,with the filtered cardiotomy liquid flowing directly onto the venousfilter 112. The venous filter 112, in turn, guides the cardiotomy liquidinto the main chamber 28 for more complete mixing with the filteredvenous blood. Thus, regardless of a volume of blood within the mainchamber 28, cardiotomy blood flow from the cardiotomy filter 204 willnot splash or “drip” into the main chamber 28; instead, a gentle,continuous flow to the venous filter 112 occurs, followed by flow intothe main chamber 28.

Ventilation of gas from the cardiotomy chamber 34 occurs through thecardiotomy defoamer 206 (e.g., gaseous microemboli removed by thecardiotomy defoamer 206) and the cardiotomy ventilation gap 236 into themain chamber 28. Gas from between the dish 202 and the turret 44 isventilated through the circumferential gap 234 and into the cardiotomychamber 34; the so-removed gas then progresses through the cardiotomyventilation gap 236 and into the main chamber 28 as described above.Ventilation of gas from the venous chamber 30 (e.g., gaseous microemboliremoved by the venous defoamer 114) occurs through the venous defoamer114, the ventilation region 184 and the venous gas pathway 186 to aspace between the dish 202 and the turret 44. The gas then passes to thecardiotomy chamber 34 and ultimately the main chamber 28 as describedabove. Gases/pressure accumulated within the main chamber 28 arerelieved from the reservoir 20 via one or more vent ports (e.g., thevent port 70 c of FIG. 2) that can be open to atmosphere or connected toa source of negative pressure.

Another cardiotomy and venous reservoir 20′ in accordance withprinciples of the present disclosure is shown in FIG. 7. The reservoir20′ is, in many respects, highly akin to the reservoir 20 (FIGS. 1A and1B) described above. The preceding descriptions of the reservoir 20apply equally to the reservoir 20′ (with like numbers referencing likeelements), subject to the following explanations. The reservoir 20′includes the housing assembly 22 (referenced generally), a venoussub-assembly 24′. and a cardiotomy sub-assembly 26′. As with thereservoir 20, the venous sub-assembly 24′ and the cardiotomysub-assembly 26′ are maintained within the main chamber 28 (referencedgenerally) of the housing assembly 22, with the venous sub-assembly 24′forming a venous chamber 30′ through which venous blood flow from thevenous inlet port 32 (FIG. 1A) is directed into the main chamber 28. Thecardiotomy self-assembly 26′, in turn, establishes a cardiotomy chamber34′ through which cardiotomy blood flow from one or more of thecardiotomy inlet ports 36 (FIG. 1A) is directed into the main chamber28.

The venous sub-assembly 24′ includes a downtube 80′, the bowl 110, thevenous filter 112, and a venous defoamer 114′. The downtube 80′ isidentical, in many respects, to the downtube 80 (FIG. 4A) describedabove, defining the lumen 116 to have a diameter that increases to thedownstream end 128. Further, the downstream end 128 is spatially locatedrelative to features of the bowl 110 as previously described. Unlike thedowntube 80, the downtube 80′ forms one or more circumferential ribs 250configured to robustly engage the venous defoamer 114′ upon finalassembly, serving to limit downward displacement (relative to theorientation of FIG. 7) of the venous defoamer 114′. The ribs 250 canassume various shapes and/or sizes (e.g., continuous or discontinuousrings), and two or more of the ribs 250 can be formed. In yet otherembodiments, the ribs 250 are omitted.

The venous defoamer 114′ is akin to the venous defoamer 114 (FIG. 4A),and is constructed from any of the materials previously described. Thevenous defoamer 114′ has a generally tubular shape, with an innerdiameter thereof sized to be received over the downtube 80′ andfrictionally interface with the ribs 250. Further, the venous defoamer114′ detines opposing, leading and trailing ends 256, 258.

The leading end 256 is longitudinally spaced from the bowl 110 by adistance selected to minimize contact with liquid venous blood withinthe venous chamber 30′ at normal or expected flow rates. Moreparticularly, by providing the ribs 250 (or other frictionalengagement-type structure) along the downtube 80′, the venous defoamer114′ is held relative to the downtube 80′ in a manner not requiring theelastomeric band 182 (FIG. 4A). By removing the band 182, the leadingend 256 can be more overtly spaced from (above) the bowl 110 (ascompared to a vertical spacing between the leading end 180 of the venousdefoamer 114 and the bowl 110 in FIG. 4A). As a result, an elevatedvolume of liquid blood can be maintained within the venous chamber 30′without contacting the venous defoamer 114′ (as compared to thereservoir 20). However, any foam associated with venous blood within thevenous chamber 30′ will still rise upwardly (relative to the orientationof FIG. 7) and contact the venous defoamer 114′ to effectuate desireddefoaming.

The trailing end 258 is longitudinally spaced from the turret 44 (i.e.,below the turret 44 relative to the orientation of FIG. 7), providing anenlarged ventilation region 260 (as compared to a size of theventilation region 184 of FIG. 4) that is open to the venous gas pathway186. Stated otherwise, a comparison of the venous defoamer 114′ of FIG.7 with the venous defoamer 114 of FIG. 4A reveals that with theconstruction of FIG. 7, a spacing between the trailing end 258 and theturret 44 is greater than that between the trailing end 183 and theturret 44 to better ensure adequate gas flow to the venous gas pathway186.

The cardiotomy sub-assembly 26′ is in many respects is identical to thecardiotomy sub-assembly 26 (FIG. 4A) described above, and includesframework 200′, a dish 202′, the cardiotomy filter 204 (hidden in theview of FIG. 7, but referenced generally), and a cardiotomy defoamer206′. As with previous embodiments, the framework 200′ maintains thecardiotomy filter 204 and the cardiotomy defoamer 206′. The dish 202′directs cardiotomy liquid flow from the cardiotomy inlet port(s) 36 tothe framework 200′ with the framework 200′, in turn, directing thecardiotomy liquid flow to the cardiotomy chamber 34′ via a guide surface208′. The cardiotomy liquid is subsequently directed to the main chamber28 via the cardiotomy filter 204, with the cardiotomy defoamer 206′positioned to remove foam from the cardiotomy liquid.

The framework 200′ is akin to the framework 200 (FIG. 4A) describedabove, and thus includes an inner post 210′, a base 212′, and the outerframe 214. The inner post 210′ is tube-like, sized to coaxially receivethe venous defoamer 114′ (as assembled over the downtube 80′). Further,the inner post 210′ forms a section of the guide surface 208′, servingto direct cardiotomy liquid flow received from the dish 202′. Thus, theguide surface 208′ along the inner 210′ is akin to the first section 216(FIG. 4A) of the inner post 210 (FIG. 4A) described above. However, asrevealed by comparison of FIGS. 4A and 7, the guide surface 208′ has anundulating shape, including a discernable radially outwardly componentin longitudinal extension below the dish 202′ (in contrast, with theconstruction of FIG. 4A, the first section 216 is primarily linear).More particularly, the guide surface 208′ is shaped so as to expand to adiameter approximating a diameter of an aperture 230′ of the dish 202′at a longitudinal location that is relatively close to the dish 202′.

For example, the guide surface 208′ can be described as being defined bya leading region 270, an intermediate region 272, and a trailing region274. The leading region 270 is aligned with, and extends downwardlyfrom, the aperture 230′ of the dish 202′, having a gentle outwardcurvature (e.g., slightly concave shape) to the intermediate region 272.A diameter defined by the leading region 270, at least adjacent thecentral aperture 230′, is less than a diameter of the central aperture230′. The intermediate region 272 extends downwardly from the leadingregion 270, and can form a slight convex curvature and/or compoundcurvature with slight convex and concave curves. Regardless, thediameter of the guide surface 208′ continues to radially expand (in thedownward direction) along the leading and intermediate regions 270, 272.In particular, at a spatial point P along the leading region 270, thediameter of the guide surface 208′ has sufficiently increased toapproximate the diameter of the central aperture 230′, with the guidesurface diameter continuing to increase (in the downward direction) fromthe spatial point P along the intermediate region 272. Finally, thetrailing region 274 extends from the intermediate region 272 to the base212′, and can have the generally convex curvature shown. Unlike theguide surface 208 (and in particular the tirst section 216) of FIG. 4A,then, the guide surface 208′ of FIG. 7 has a non-linear shape orcurvature relative to the central axis of the inner post 210′,increasing in diameter in the downward direction, including an outerdiameter that is greater than the diameter of the central aperture 230′.As described in greater detail below, with this relationship, possibleintermittent liquid flow (e.g., drips) from the central aperture 230′will contact the guide surface 208′ well above the base 212′, and thusis less likely to splash upon contact. As a point of reference, althoughthe spatial point P is not identitied in FIG. 4A, a comparison of FIGS.4A and 7 reveals that the spatial point at which the diameter of theguide surface 208 approximates the diameter of the central aperture 230is well below (i.e., further spaced from) the dish 202 with theconstruction of FIG. 4A. Relative to a linear length of the guidesurface 208′ in downward extension from the dish 202, the spatial pointP at which the diameter of the guide surface 208′ has expanded to equalthe diameter of the aperture 230′ is less than 50% of the linear length;in other embodiments, less than 40%. The gentle undulating shape of theguide surface 208′ enhances smooth flow within the cardiotomy chamber34′.

The base 212′ is akin to the base 212 (FIG. 4A) described above, andextends radially outwardly and downwardly from the inner post 210′.

The dish 202′ is highly akin to the dish 202 (FIG. 4A) described aboveand has a funnel-like shape forming the flow surface 232 terminating atthe central aperture 230′. The central aperture 230′ is defined by aninner face 280 of the dish 202′, with the dish 202′ forming a knife edge282 at an intersection of the inner face 280 with a bottom surface 284of the dish 202′. As described above, the diameter of the centralaperture 230′ is greater than a diameter of the inner post guide surface208′ relative to a location of the guide surface 208′ radially alignedwith the central aperture 230′, creating a circumferential gap 286. Thegap 286 is open to the cardiotomy chamber 34′. As compared to thecircumferential gap 234 (FIG. 4A) of the reservoir 20 (FIG. 4A), a size(e.g., radial width) of the circumferential gap 286 associated with thereservoir 20′ is increased. For example, the circumferential gap 286 canhave a radial width on the order of 0.200 inch as compared to a radialwidth of 0.100 inch for the circumferential gap 234. The enlargedcircumferential gap 286 (as compared to the circumferential gap 234)minimizes the likelihood of a blood “film” forming across thecircumferential gap 286. It will be recognized, however, that theenlarged circumferential gap 286 may be more prevalent to drippingand/or splashing-type flow into the cardiotomy chamber 34′ at lower flowrates. To avoid these occurrences, the guide surface 208′ has thecurved, radially-expanding (in the downward direction) diameterdescribed above, thereby ensuring that any blood drops from the dish202′ will fall upon the guide surface 208′ at location in relativelyclose proximity to the dish 202′ (as opposed to the relatively lengthydistance between the dish 202′ and the base 212′). Further, the presenceof the knife edge 282 better ensures that any liquid drips or dropsthrough the central aperture 230′ will fall in a relatively linear orstraight pattern, and thus on to the closely-positioned guide surface208′ along the intermediate region 274.

The cardiotomy defoamer 206′ is highly akin to the cardiotomy defoamer206 (FIG. 4A) described above, and can be formed of the materialspreviously described. With the embodiment of FIG. 7A, however, thecardiotomy defoamer 206′ terminates at a bottom edge 290 that islongitudinally spaced from the base 212″ by a distance greater than thatassociated with the previous embodiment reservoir 20 (FIG. 4A). As aresult, even with the enlarged diameter inner post 210′ (as compared tothe post 210 of FIG. 4A), by raising the bottom edge 290 to the extentreflected in FIG. 7, a sufficient volume is provided beneath thecardiotomy defoamer 206′ to permit passage of expected volumes ofcardiotomy liquid without directly contacting the cardiotomy defoamer206′.

The reservoir 20′ operates as part of an extracorporeal blood circuit inmatters akin to the reservoir 20 (FIG. 4A). For example, venous bloodenters the lumen 116 of the downtube 80′, and is directed onto the bowl110 and into the venous chamber 30′. The so-delivered venous bloodpasses through the venous filter 112 and into the main chamber 28. Airbubbles or other gaseous microemboli associated with the venous bloodcontacts the venous defoamer 114′, flows through the ventilation region260, and is released from the reservoir 20′ via a vent associated withthe housing assembly 22 (e.g., gas flow occurs from the venous defoamer114′ into the venous gas pathway 186 between the turret 44 and the dish202′ where it is then relieved from the reservoir 20′). Cardiotomyliquid flows into the dish 202′, and is directed along the flow surface232′, through the circumferential gap 290, along the guide surface 208′and into the cardiotomy chamber 34′. The cardiotomy filter 204 filtersthe cardiotomy liquid (e.g., removes particulate microemboli) prior todispensement into the main chamber 28. The cardiotomy defoamer 206′removes air bubbles or other gaseous microemboli from the cardiotomyliquid, with the so-removed gaseous microemboli being vented from thereservoir 20′.

Ventilation of gas from the cardiotomy chamber 34′, from the spacebetween the dish 202′ and the turret 44, and from the venous chamber 30′to the main chamber 28 (and ultimately to atmosphere from the mainchamber 28) is akin to the above explanation with respect to thereservoir 20 of FIG. 4A. In general terms, gas in the cardiotomy chamber34′ flows to the main chamber 28 via the cardiotomy ventilation gap 236.Gas from the space between the dish 202′ and the turret 44 flows throughthe circumferential gap 286 and then to the cardiotomy ventilation gap236. Gas from the venous chamber 30′ and/or the venous defoamer 114′flows through the ventilation region 260 and the venous gas pathway 186to the space between the dish 202′ and the turret 44, and then thecircumferential gap 286 and the cardiotomy ventilation gap 286. Thoughnot shown in FIG. 7, the reservoir 20′ includes one or more ventilationports (e.g., the port 70 c of FIG. 2) through which gas/pressure in themain chamber 28 is relieved or removed.

With the constmction of FIG. 7, the reservoir 20′ minimizesopportunities for the formation of blood films within the cardiotomysub-assembly 26′ (e.g., across the circumferential gap 286), while atthe same time minimizing opportunities for splashing-type flow (e.g., byminimizing a longitudinal drip distance between the cardiotomy dishaperture 230′ and the cardiotomy guide surface 208′, the undulatingshape of the guide surface 208′, etc.). Further, desired vent patternsare facilitated (e.g., from the venous defoamer 114′). These features,in turn, greatly reduce the formation of gaseous microemboli, as well asremove microemboli present in the venous and cardiotomy blood flowsdelivered to the reservoir 20′.

Reservoirs 20, 20′ of the present disclosure provide a markedimprovement over previous designs, and serve to gently and smoothlydirect and combine the incoming flow of cardiotomy and venous blood.Venous blood flow to the venous chamber 30, 30′ and then the mainchamber 28 experiences substantially laminar flow even at low flowrates, with minimal or no splashing to the main chamber 28, and iscontinuously directed along smooth, curving surfaces. Similarly,cardiotomy liquid smoothly flows to the main chamber 28, and isminimally subjected to splashing-type actions. As a result, thereservoir 20, 20′ minimizes the opportunities for trauma-inducingevents. The flow is smooth and controlled in order to minimize bloodtrauma and improve air handling.

The reservoir 20, 20′ is highly conducive to various perfusionapplications, and in some embodiments is highly beneficial for smallpatients (e.g., neonates, infants, children, small adults, etc.). Forexample, at the flow rates and volumetric capacity typically associatedwith pediatric or small adult procedures (e.g., a main chamber 28maximum volume on the order of 1,200 milliliters), substantially laminarflow of cardiotomy and venous blood through the reservoir 20, 20′ issubstantially maintained. Further, the reservoir 20, 20′ minimizes theformation of air bubbles, yet is configured to readily remove formed airbubbles. The maximum flow rate supported by reservoirs of the presentdisclosure is, in some embodiments, highly useful with pediatricpatients. In some embodiments, the reservoir 20, 20′ is sized to providea maximum flow rate applicable to any pediatric category (neonate,infant, or child), and is on the order of 4.55 liters/minute. In otherembodiments, the reservoir 20, 20′ is provided to a clinician in two ormore different sizes, each with a different rated maximum flow rate. Forexample, a tirst neonate/infant reservoir having a rated maximum flowrate of 2.2 liters/minute; a second, pediatric/small adult reservoirhaving a rated maximum flow rate of greater than 1.8 liters/minute andless than 5.0 liters/minute; and a third, adult reservoir having a ratedmaximum flow rate of greater than 5.0 liters/minute (up to 7.0liters/minute). As a point of reference, expected maximum flow rateparameters for pediatric patients (based on age, weight, and height)that are met by contigurations of the present disclosure include:neonates (birth—one month) of 0.96 liters/minute; infants (one month—twoyears) of 1.83 liters/minute; and child/pediatric (two years—twelveyears) of 4.55 liters/minute.

Further, cardiotomy and venous reservoirs in accordance with the presentdisclosure may include a cardiotomy flow guide surface having anundulating shape (e.g., the guide surface 208′ of FIG. 7) as describedabove. Additional cardiotomy flow guide surface shapes are contemplatedherein, for example any shape that functions like the undulating guidesurface 208′ to reduce the amount of dynamic fluid hold-up in thecardiotomy chamber 34′ as compared to that of a cardiotomy chamberhaving a non-undulated guide surface; or a shape that functions tominimize the volume of fluid held behind cardiotomy filter 204 byoptimizing fluid “break through” (i.e., the ability of fluid to flow outof the cardiotomy chamber 34′). For example, the shape of the cardiotomyflow guide surface can create an increased fluid level in the cardiotomychamber (i.e., an increase in head height) by displacing volume in thecardiotomy chamber (e.g., by creating a narrowed cardiotomy chamberhaving a reduced volume). As used herein, the phrase “dynamic hold-upvolume” is in reference to the volume of fluid held within thecardiotomy chamber 34, 34′ and behind the cardiotomy filter 204, withconstant introduction of fresh fluid counteracting withdrawal of heldfluid to maintain a constant fluid level. The dynamic hold-up volumecontributes to the overall “prime volume” attributable to the device,the reduction of which is desirable.

As indicated above, the reservoir 20, 20′ can include a wide variety ofports useful for facilitating desired connections within a perfusioncircuit. As a point of reference, the design of small devices, such asthe cardiotomy and venous reservoir of the present disclosure forpediatric applications, that provide all the connection sites andconfigurational flexibility required by different customers anddifferent procedures is extremely challenging. Existing combinationcardiotomy and venous reservoir devices typically have standard barbtubing connection sites, luer ports, and other sampling and monitoringsites crowded into spaces that are not ergonomically friendly. Toaddress these concerns while still offering all desired connectionsites, in some embodiments of the present disclosure, flexible,kink-resistant extensions and/or interchangeable connector mechanismsare employed. For example, FIG. 8A is a perspective view of a portion ofa cover assembly 300 useful with an alternative reservoir (not shown) inaccordance with the present disclosure. The cover assembly 300 can beassembled to the housing 40 (FIG. 1A) described above. With this inmind, the cover assembly 300 includes a cover 302, one or more extensionconnectors 304 a-304 c, and one or more snap-fit connector ports 306a-306 e. As described below, the extension connectors 304 a-304 c andthe snap-fit connector ports 306 a-306 e are fluidly open to acorresponding hole through a thickness of the cover 302 (e.g., FIG. 8Aidentifies hole 308 a in the cover 302 and associated with the firstsnap-fit connector port 306 a) so as to establish a fluid passageway tochamber(s) (not shown) encompassed by the cover 302 upon final placementof the cover assembly 300.

The extension connectors 304 a-304 c each include an extension body 310and a port connector 312. The extension body 310 is a kink-resistanttubing (e.g., flexible tubing with a helically-wound spring disposed orembedded therewithin). In some embodiments, the port connector 312 isconfigured to receive and maintain a luer-type connection piece. Withthis construction, the extension connectors 304 a-304 c can be placed invery close proximity to one another (thereby conserving space along thecover 302) and can be readily articulated to a desired orientation by auser, thereby enhancing the ease with which connections to the reservoir(e.g., venous inflow, sampling, ventilation, temperature monitoring,cardiotomy inflow, etc.). Thus, though not fully depicted in thefigures, the extension connectors 304 a-304 c can bend in any directionto provide a desired set-up orientation that might otherwise requirerotafional of an individual one of the extension connectors 304 a-340 c(e.g., venous inlet) or of the corresponding turret where provided(e.g., cardiotomy return line).

The extension connectors 304 a-304 c can be provided to a user apartfrom the cover 302 (e.g., as part of an accessory package) forsubsequent assembly, or can be more permanently affixed. While three ofthe extension connectors 304 a-304 c are shown in FIG. 8A, in otherconfigurations, a greater or lesser number are also acceptable.

The snap-fit connector ports 306 a-306 e can be generally identical, andeach include a receptacle body 320 and a snap-fit connector mechanism322. The receptacle body 320 can be cylindrically-shaped, and is sizedto selectively receive a separate connector as described below. In thisregard, the receptacle body 320 can be integrally formed with the cover302 (e.g., as part of a molding process, resulting in the receptaclebody 320 being defined as a raised column projecting outwardly from amajor face of the corner 302) or can be separately formed andsubsequently assembled to or within a corresponding hole (e.g., the hole308 a) in the cover 302.

Regardless of whether the receptacle body 320 is formed apart from thecover 302, the connector mechanism 322 is configured to facilitatereleasable, fluid-sealed, snap-fit connection of a separate connectorwithin the corresponding receptacle body 320 in a manner permitting theconnector to rotate relative to the receptacle body 320. The connectormechanism 322 can include various components, such as a spring (notshown) and an actuator (e.g., the tab 324 identified in FIG. 8A for thethird snap-fit connector port 306 c) that are incorporated into thecorresponding receptacle body 320 in some embodiments.

As shown in FIG. 8B, the cover assembly 300 allows for provision of widevariety connection devices that are ergonomically accessible and meetthe needs of numerous end users. Alternatively, however, conventionalconnectors can be provided with the reservoirs of the presentdisclosure.

The snap-fit connector ports 306 a-306 e are available for fluidlyreceiving (e.g., snap-fitting in place) an appropriate connector device330 a-330 e (e.g., barbed connector, bent or curved tubing, etc.). Withapplications in which the end user does not require fluid interface witheach of the connector ports 306 a-306 e, a cap may be snap-fitted to thecorresponding, unused receptacle(s) 320 thereby conserving space. Theoptional snap-in-place connector ports 306 a-306 e provide an ability ofeach of the connectors 330 a-330 e to rotate independent of the others(i.e., the connector 330 a can rotate within the receptacle body 320 ofthe corresponding snap-fit connector port 306 a independent of theremaining connectors 330 b-330 e). This feature provides optimalflexibility in routing tubes to and from the reservoir (not shown), andcan replace the optional rotatable turret described above. Further,desired rotation of the connectors 330 a-330 e provides at least somestrain relief for the corresponding connection site. Also, the snap-fitconnector ports 306 a-306 e facilitate use of differently-sizedtubing/adapters in conjunction with a desired blood handling system. Asa point of reference, with many infant or other pediatric procedures,the same-sized reservoir will be used, but the corresponding tubing sizewill differ as a function of optimized prime volume relative to maximumrequired flow rates. With the optional, snap-fit connector ports 306a-306 e of the present disclosure, separate adapters are not necessaryto reduce or step-up the size of the tubing actually employed. Instead,a properly sized connector (not shown, but akin to the connectors 330b-330 c) can simply be assembled to the desired snap-fit connector port306 a-306 e (e.g., interchanged with one of the existing connectors 330a-330 e), and the tubing connected thereto.

In some embodiments, at least the connector mechanism 322 is“pre-connected” to the separate tubing (e.g., as part of the customtubing pack) rather than provided directly with the cover 302.Regardless, because the connector mechanism 322 is not integrally moldedto or with the cover 302, a user is afforded greater flexibility. Forexample, the cover assembly 300 can include the receptacle body 320 (orsimilar feature), with the separate tubing carrying the correspondingconnector mechanism 322 for selective, rotatable assembly thereto. Inrelated embodiments, the snap-fit connector port 306 a-306 e is affixedto the tubing and serves as the connector for releasable assembly to thecover 302 (e.g., the connector port 306 a-306 e serves as one of theconnectors 330 a-330 e of FIG. 8B and is selectively assembled to acorresponding hole in the cover 302 (e.g., the hole 308 a of FIG. 8A)).

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure. For example, while the snap-fit andthe extension connectors have been described as being useful with acardiotomy and venous blood reservoir, other extracorporeal devices inaddition to reservoir can equally benefit. Thus, for example, theconnectors can be employed with oxygenators, heat exchangers, pumps,etc. In more general terms, then, some aspects of the present disclosurerelate to a perfusion device requiring fluid connection to one or moreother components of perfusion system and having a fluid connectorassembly including a cover and at least one snap-fit, rotatableconnector port removably assembled thereto. The perfusion device caninclude various other components useful for performing a perfusionprocedure, such as a pump, filter, reservoir, oxygenator, heatexchanger, etc. Also, one or more flexible, kink-resistant extensionconnectors can be provided with the fluid connector assembly.

1. A cardiotomy and venous blood reservoir comprising: a housingassembly forming a main chamber; a venous inlet port; a venoussub-assembly forming a venous chamber fluidly between the venous inletport and the main chamber, the venous sub-assembly including: a downtubedefining an upstream region, a downstream region, and a lumen extendingtherethrough, wherein: the upstream region extends from the venous inletport, the downstream region extends from the upstream region andterminates at a downstream end located within the main chamber, adiameter of the lumen increases along at least a portion of thedownstream region to the downstream end, a bowl disposed within thevenous chamber and forming a floor surface facing the downstream end forreceiving venous blood flow from the lumen; a cardiotomy inlet port; anda cardiotomy sub-assembly forming a cardiotomy chamber fluidly betweenthe cardiotomy inlet port and the main chamber, the cardiotomysub-assembly including: a dish defining a flow surface open to thecardiotomy inlet port and terminating at a central aperture, an innerpost extending downwardly relative to the dish, the inner postco-axially disposed over the downtube and forming a guide surfacedefined by a leading segment received within the central aperture andhaving a diameter less than a diameter of the central aperture, and atrailing segment extending downwardly from the leading segment, thetrailing segment forming an undulating curvature and defining a diametergreater than the diameter of the central aperture.
 2. The reservoir ofclaim 1, wherein the increasing diameter of the lumen is exhibited alonga majority of a length of the downtube in extension from the venousinlet port.
 3. The reservoir of claim 1, wherein the chamber is definedby a height, and further wherein the downtube includes a chamber sectionhaving a length of at least one-half the height, and even furtherwherein the lumen increases in diameter along an entirety of the chambersection.
 4. The reservoir of claim 1, wherein the floor surface forms aprotrusion extending upwardly and radially inwardly from a bottom faceof the floor surface to a center, wherein the center is aligned with thelumen and spaced below the downstream end, and further wherein the floorsurface forms a smooth curve in transition from the bottom face to theprotrusion.
 5. The reservoir of claim 1, wherein the venous sub-assemblyfurther includes: a venous filter circumferentially surrounding andimmediately adjacent the floor surface.
 6. The reservoir of claim 1,wherein the venous sub-assembly further includes: a venous defoamerdisposed about the downtube, the venous defoamer terminating at aleading end facing the bowl, the leading end being spatially positionedabove the downstream end.
 7. The reservoir of claim 6, wherein thevenous sub-assembly further includes: a venous filter circumferentiallysurrounding the bowl, wherein the reservoir is constructed such thatvenous blood is directed through the downtube and into the main chambervia a flow path defined by the floor surface and the venous filter, andfurther wherein the venous defoamer is spaced from the flow path.
 8. Thereservoir of claim 1, wherein the venous sub-assembly further includes:a venous filter circumferentially surrounding the bowl to establish avenous chamber; wherein the cardiotomy sub-assembly establishes acardiotomy flow path from the cardiotomy inlet port to the main chamber,the cardiotomy flow path having an outlet side located above the venousfilter.
 9. The reservoir of claim 8, wherein the outlet side is fluidlyassociated with the venous filter such that cardiotomy liquid flow fromthe outlet side of the cardiotomy flow path travels along the venousfilter and into the main chamber.
 10. The reservoir of claim 8, whereinthe cardiotomy sub-assembly further includes: framework maintaining acardiotomy filter and establishing the guide surface for directing flowof cardiotomy liquid from the cardiotomy inlet port, through thecardiotomy filter, and to the outlet side; and a cardiotomy defoamermounted to the framework at a location spaced from the guide surface.11. The reservoir of claim 10, wherein the framework includes: an outerframe radially spaced from the inner post; wherein the cardiotomydefoamer is mounted to the outer frame such that the guide surfaceextends below a lower end of the cardiotomy defoamer.
 12. The reservoirof claim 11, wherein the cardiotomy sub-assembly further includes: avenous defoamer mounted between the downtube and the inner post.
 13. Thereservoir of claim 1, wherein the cardiotomy sub-assembly is configuredsuch that cardiotomy liquid from the cardiotomy inlet port flows alongthe flow surface and to the guide surface of the inner post via theaperture.
 14. The reservoir of claim 1, wherein the dish forms a knifeedge at the central aperture.
 15. The reservoir of claim 1, wherein theguide surface a plurality of discrete curvatures in longitudinalextension from the dish.